Many cardiac procedures employ catheters and other similar devices that are manipulated into the chambers of the heart. Electrophysiology (EP) is a discipline in which catheters are fed into the open chambers of the heart, generally gaining access via the great veins. The distal section of the catheter is manually manipulated within the heart by tactile control of the proximal catheter section, which can be up to four feet or more from the distal section, often in the groin area of the patient. Precise manipulation of the catheters is desired to record the electrical signals emanating from the endocardial surfaces. It is desirable to drag the catheters along curved paths, maintaining contact with the inside or endocardial surface of the heart chambers, even as the heart muscle constricts and relaxes. It is further most desirable to identify the anatomical features of the heart which are in contact with the catheter, and to record their location in space. It is then often desirable to return to a specific location to either re-record the electrical signal or to apply energy through the catheter to ablate tissue which is involved in the generation of abnormal electrical signals or arrhythmias.
Precise manipulation of the distal end of recording and ablation catheters from the proximal end is generally difficult and often impossible because of the squeezing motions of the heart, the convoluted anatomy of the heart chambers (especially when the catheter must pass through one chamber to access an adjacent chamber), and the presence of anatomical structures such as cords and tribiculae.
The catheters presently used for these procedures are usually navigated using a mechanically navigated guide wire, or arc themselves directly mechanically navigated. These mechanically navigable catheters are difficult to accurately control, and become increasingly so as the catheter twists and turns. One difficulty with presently available cardiac catheters is that it is difficult to determine when the catheter is in contact with the surface of the heart. Moreover, even when the catheter is in contact with the surface of the heart, it is not possible to determine the contact pressure.